Recently, there has been a great interest in the field of molecular electronics. The potential for molecular memory devices has been studied where charge storage can be used to read and/or write data. Detailed information with respect to this topic can be found in the following publications: Harell, S. et al., Microelectron Eng., 30, 11 (1996); Reed, M. A. et al., Since, Volume 278, 252-254 (1997); Reed, M. A., Proc. IEEE, Volume 87, 652-658 (1999); Roth, K. M. et al., J. Vac. Sci. Technol. B., 18(5), 2359 (2000); and Tour, K. M. et al., J. Am. Chem. Soc., 177, 9259 (1999).
A common architecture proposed to incorporate charge molecules is a crossbar array structure. A typical crossbar array includes two sets of lines that run perpendicular to each other. These lines may be separated by a gap that is typically filled with molecules. This arrangement may provide a circuit having a data storage capability.
A typical fabrication process for a crossbar array structure involves depositing and patterning a first set of metal lines. After the first set of lines is deposited and patterned, the molecules may be self-assembled. After the molecules are self-assembled, a second set of metal lines may be deposited and patterned to complete the crossbar array structure. This fabrication process may cause the molecules located in the gap between the first and second set of metal lines to be damaged or destroyed during the deposition and patterning of the second set of metal lines. For example, the molecules in the gap between the first and second metal lines may be destroyed by metal ions diffusing down through the molecules during the deposition of the second set of metal lines.
Alternative methods of fabricating crossbar array structures have been proposed that address the problems with existing fabrication methods. One alternative method, for example, is discussed in co-assigned U.S. patent application Ser. No. 10/046,499 entitled Molehole Embedded 3-D Crossbar Architecture Used in Electrochemical Molecular Memory Device filed on Oct. 26, 2001.